Certain aerial forms may be classed as loop and straightaway accordingly as they are connected and led into the station. In the straightaway form of antenna, the wires are connected together as a whole and one rat-tail led into the station. In the loop form the wires are all connected together and divided into two sections. Two wires are led into the station.
The loop form gives slightly better results in a short aerial, but in most cases the straight away is decidedly the most efficient.
LESSON FOURTEEN. THE WIRELESS COIL.
The induction coil used for wireless telegraph purposes differs from the ordinary coil commonly employed in the laboratory in that it is usually built in a more substantial manner and gives a heavier, more powerful discharge from the secondary.
Induction coils of this type are usually enclosed in a strong wooden case filled with insulating compound and are sometimes termed box coils. They are fitted with an interrupter arranged to give a very long period of "make" and a short "break."
Coils giving sparks greater than six inches in length are usually provided with an independent interrupter which may be one of several types.
Fig. 30. Wireless Spark Coil.
The ordinary independent interrupter consists of the usual form of interrupter, but is operated by the magnetism of a separate electromagnet in place of that of the coil primary itself. An independent interrupter of this type is usually provided with screws for adjusting the speed, and the duration of make and break.
